Humidifying apparatus

ABSTRACT

A humidifying apparatus includes a base, a water tank removably mounted on the base for supplying water to a chamber of the base, and a motor-driven impeller for generating an air flow over water stored in the chamber. An ultraviolet radiation emitting lamp irradiates water stored in the chamber. The air flow is humidified with water from the chamber, and conveyed by an outlet duct towards an air outlet for emission from the apparatus. A detachable section of the water tank is opaque to ultraviolet radiation and is positioned over the chamber when the water tank is mounted on the base. The detachable section of the water tank includes an air inlet of the outlet duct and a flange for occluding a peripheral portion of the chamber.

REFERENCE TO RELATED APPLICATIONS

This application claims the priority of United Kingdom Application No.1413428.2, filed Jul. 29, 2014, the entire contents of which areincorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a humidifying apparatus. In a preferredembodiment, the present invention provides a humidifying apparatus forgenerating a flow of moist air and a flow of air for dispersing themoist air within a domestic environment, such as a room, office or thelike.

BACKGROUND OF THE INVENTION

Domestic humidifying apparatus is generally in the form of a portableappliance having a casing comprising a water tank for storing a volumeof water, and a fan for creating a flow of air through an air duct ofthe casing. The stored water is conveyed, usually under gravity, to anatomizing device for producing water droplets from the received water.This device may be in the form of a heater or a high frequency vibratingdevice, such as a transducer. The water droplets enter the flow of airpassing through the air duct, resulting in the emission of a mist intothe environment. The appliance may include a sensor for detecting therelative humidity of the air in the environment. The sensor outputs asignal indicative of the detected relative humidity to a drive circuit,which controls the transducer to maintain the relative humidity of theair in the environment around a desired level. Typically, the actuationof the transducer is stopped when the detected relative humidity isaround 5% higher than the desired level, and is restarted when thedetected relative humidity is around 5% lower than the desired level.

It is known to provide an ultraviolet radiation (UV) emitting lamp orother UV generator to sterilize water that is conveyed to the atomizingdevice. For example, U.S. Pat. No. 5,859,952 describes a humidifier inwhich the water supplied from a tank is conveyed through a sterilizingchamber before being conveyed by a pipe to a chamber containing anultrasonic atomizer. The sterilizing chamber has a UV transparent windowbeneath which a UV lamp is located to irradiate water as it passesthrough the sterilizing chamber. U.S. Pat. No. 7,540,474 describes ahumidifier in which the water tank includes a UV transparent tube forconveying water to an outlet of the tank, and a main body upon which thetank is mounted includes a UV lamp which irradiates water as it passesthrough the tube to the outlet.

WO 2013/132222 describes a humidifier which comprises a body and anannular nozzle detachably mounted on the body. The body comprises a baseand a water tank removably mounted on the base. A motor-driven impellerlocated within the base draws an air flow into the humidifier throughair inlets located in the outer casing of the base. A first airpassageway located downstream from the impeller conveys a first part ofthe air flow to an annular first interior passage within the nozzle. Thefirst part of the air flow is emitted from a first air outlet of thenozzle. A second air passageway located downstream from the impellerconveys a second part of the air flow over a water reservoir whichreceives water from the water tank. Transducers located within the waterreservoir atomize water stored in the water reservoir to humidify thesecond part of the air flow. An outlet duct defined by the water tankconveys the humidified air flow to an annular second interior passage ofthe nozzle. The humidified air flow is emitted from a second air outletof the nozzle so that the humidified air flow becomes entrained withinthe air emitted from the first air outlet of the nozzle.

The base has a relatively wide cylindrical outer wall, a relativelynarrow cylindrical inner wall located above and co-axial with the outerwall, and a recessed annular wall which extends between the inner walland the outer wall. These walls of the base define the water reservoir,and so the water reservoir is exposed when the water tank is removedfrom the base. The water reservoir includes a UV transparent tubehousing a UV lamp for irradiating water stored in the water reservoir,and baffle plates for guiding water entering the water reservoir fromthe water tank over the tube so that it is irradiated by the UV lampbefore being atomized by the transducers. The water tank is annular inshape, and is mounted by the user on the annular wall of the base so asto surround the inner wall of the base. The base includes a proximitysensor for detecting that the water tank has been mounted on the base. Adrive circuit deactivates the motor, the UV lamp and the transducers inresponse to signal received from the proximity sensor indicating thatthe water tank has been removed from the base.

SUMMARY OF THE INVENTION

In a first aspect, the present invention provides humidifying apparatuscomprising a base comprising a chamber, a water tank removably mountedon the base for supplying water to the chamber, an impeller and a motorfor driving the impeller to generate an air flow, an inlet duct forconveying the air flow to the chamber, humidifying means for humidifyingthe air flow with water from the chamber, an ultraviolet radiationgenerator for irradiating water stored in the chamber, and an outletduct for conveying the humidified air flow from the chamber, wherein adetachable section of the apparatus is opaque to ultraviolet radiationand is positioned over the chamber, the detachable section comprising anair inlet of the outlet duct and a flange for occluding a peripheralportion of the chamber.

In addition to providing at least part of an outlet duct for conveying ahumidified air flow away from the chamber, the detachable section of theapparatus can also provide a cover for the chamber. Forming thedetachable section from material which is opaque to ultravioletradiation can inhibit any leakage of ultraviolet radiation both throughthe detachable section of the apparatus and from the peripheral portionof the chamber. The flange also inhibits leakage of air from theperipheral portion of the chamber. Having these features formed in adetachable section of the apparatus can enable the chamber and thedetachable section to be easily cleaned by the user when the detachablesection has been detached from the apparatus.

The detachable section of the apparatus is preferably detachablyconnected to the water tank so that it is positioned over the chamberwhen the water tank is mounted on the base, but alternatively thedetachable section of the apparatus may be detachably connected to thebase.

Preferably, the detachable section also comprises an air outlet of theinlet duct. The air outlet of the inlet duct is preferably co-planarwith the air inlet of the outlet duct, so that the air inlet of theoutlet duct and the air outlet of the inlet duct are located at the samedistance above the level of the water stored in the chamber. The airoutlet of the inlet duct is preferably located adjacent to the air inletof the outlet duct to minimize the length of the flow path between theair outlet of the inlet duct and the air inlet of the outlet duct.

The detachable section preferably comprises a wall depending from atleast part of the flange for guiding the air flow from the air outlet ofthe inlet duct towards the air inlet of the outlet duct. The wall ispreferably annular in shape and positioned so as to delimit, and so toextend about, a flow channel located directly beneath the air outlet ofthe inlet duct and the air inlet of the outlet duct.

If the ultraviolet radiation generator is omitted from the apparatus,then the detachable section of the apparatus need not be formed frommaterial which is opaque to ultraviolet radiation, and the flange mayalso be omitted. In a second aspect, the present invention provideshumidifying apparatus comprising a base comprising a chamber, a watertank removably mounted on the base for supplying water to the chamber,an impeller and a motor for driving the impeller to generate an airflow, an inlet duct for conveying the air flow to the chamber,humidifying means for humidifying the air flow with water from thechamber, and an outlet duct for conveying the humidified air flow fromthe chamber, wherein a detachable section of the apparatus is positionedover the chamber, the detachable section comprising an air outlet of theinlet duct, an air inlet of the outlet duct, the air outlet of the inletduct being positioned adjacent to the air inlet of the outlet duct, andan annular wall for delimiting a flow channel located directly beneaththe air outlet of the inlet duct and the air inlet of the outlet duct.

When the chamber is filled with water to a maximum level, the annularwall preferably extends into the water stored in the chamber,establishing an interface between the annular wall and the stored waterwhich forms a seal for inhibiting the leakage of air from the flowchannel.

The detachable section may comprise an air inlet of the inlet duct, withthe base comprising an air passageway for conveying the air flow fromthe impeller to the air inlet of the inlet duct. The air inlet of theinlet duct is preferably arranged on a side wall of the detachablesection which faces the base, the base comprising an air flow port foremitting the air flow towards the air inlet of the inlet duct.

The humidifying means preferably comprises a transducer for atomizingwater stored in the chamber. The air inlet of the outlet duct ispreferably located directly above the transducer.

The water tank is preferably annular in shape, and is mounted on thebase so as to surround at least part of the base. For example, the basepreferably comprises a cylindrical or tubular wall which surrounds themotor and the impeller, and the water tank is preferably mounted on thebase so as to surround this tubular wall. The water tank preferablycomprises an annular inner wall which is opaque to ultraviolet radiationand an annular outer wall which is transparent to visible light to allowa user to see the amount of water remaining in the tank. The detachablesection is preferably detachably connected to the annular inner wall ofthe water tank, for example by a releasable catch.

The outlet duct may comprise a plurality of sections which extendbetween the air inlet of the outlet duct and at least one air outlet ofthe outlet duct. The outlet duct preferably comprises an inlet sectionand an outlet section, and wherein the detachable section of theapparatus defines the inlet section of the outlet duct, and thedetachable section of the apparatus and the annular inner wall of thewater tank together define the outlet section of the outlet duct. Thedetachable section preferably includes a seal for engaging the annularinner wall of the water tank to inhibit leakage of the humidified airflow from between these two components.

In a preferred embodiment, the outlet duct comprises a plurality of airoutlets. For example, the outlet duct may be bifurcated into a pair ofduct branches, with each of the branches comprising a respective airoutlet of the outlet duct. The outlet duct may be bifurcated to allowthe duct to convey the humidified air flow about or around part of theapparatus, allowing the apparatus to maintain a compact appearance. Forexample, the apparatus may comprise an air outlet detachably mounted onthe base, and releasing means for releasing the air outlet for removalfrom the base, the releasing means comprising a user operable buttonmounted on the base. The outlet duct may be bifurcated into a pair ofduct branches between which the button is positioned.

As mentioned above, the detachable section preferably forms part of, oris connected to, the water tank, and so the humidified air flow ispreferably emitted from part of the water tank into the air outlet. Thewater tank preferably comprises a seal for engaging the air outlet and asupport for supporting the seal, the detachable section being detachablyconnected to the support. The support and the seal preferably compriseat least one aperture for conveying the humidified air flow from theduct to the air outlet. The seal preferably comprises a relatively rigidframe and a relatively flexible, resilient part carried by the frame forengaging the air outlet and for urging the frame towards the air outlet.The frame is preferably connected to the support so as to allow movementof the seal relative to the support. The frame may also be detachablefrom the support to allow the seal to be cleaned or replaced by theuser. The resilient part of the seal may comprise a first section whichis surrounded by the frame for engaging the air outlet, and a secondsection which is located between the frame and the support for urgingthe frame towards the air outlet. The second section of the resilientpart of the seal may have an undulating or bellows shape. The firstsection of the resilient part of the seal may also have an undulating orbellows shape.

In a third aspect, the present invention provides humidifying apparatuscomprising, a base comprising a chamber, a water tank removably mountedon the base for supplying water to the chamber, an impeller and a motorfor driving the impeller to generate an air flow, an inlet duct forconveying the air flow to the chamber, humidifying means for humidifyingthe air flow with water from the chamber, and an outlet duct forconveying the humidified air flow from the chamber to an air outlet ofthe apparatus, the outlet duct being bifurcated into a pair of ductbranches, each of the branches comprising a respective air outlet of theoutlet duct, wherein a detachable section of the apparatus is positionedover the chamber, the detachable section comprising an air inlet of theoutlet duct and at least partially defining said duct branches, andwherein the water tank comprises a seal for engaging the air outlet ofthe apparatus and a support for supporting the seal, and wherein thedetachable section of the apparatus is detachably connected to thesupport.

Features described above in connection with the first aspect of theinvention are equally applicable to each of the second and third aspectsof the invention, and vice versa.

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of the present invention will now be described, by way ofexample only, with reference to the accompanying drawings, in which:

FIG. 1 is a front perspective view of a humidifying apparatus;

FIG. 2 is a front view of the humidifying apparatus;

FIG. 3 is a rear view of the humidifying apparatus;

FIG. 4(a) is a side sectional view of the humidifying apparatus takenalong line A-A in FIG. 2, FIG. 4(b) is a close up of a first part ofFIG. 4(a), FIG. 4(c) is a close up of a second part of FIG. 4(a), FIG.4(d) is a close up of a third part of FIG. 4(a), FIG. 4(e) is a frontsectional view of the humidifying apparatus taken along line B-B in FIG.4(a), and FIG. 4(f) is a close up of a part of FIG. 4(e);

FIG. 5(a) is a front view of a nozzle of the humidifying apparatus, FIG.5(b) is a bottom sectional view taken along line C-C in FIG. 5(a), andFIG. 5(c) is a close-up of part of FIG. 5(b);

FIG. 6(a) is a rear perspective view, from below, of the nozzle, FIG.6(b) is a rear view of the nozzle, and FIG. 6(c) is a close up view ofarea D of FIG. 6(b);

FIG. 7(a) is a rear view of the nozzle with part of a housing of thenozzle removed, and FIG. 7(b) is a close up view of area E of FIG. 7(a);

FIG. 8(a) is a front view of a base of the humidifying apparatus, FIG.8(b) is a front perspective view, from above, of the base, FIG. 8(c) isa top view of the base, and FIG. 8(d) is a section view taken along lineK-K in FIG. 8(c);

FIG. 9(a) is a front perspective view, from above, of a water tank ofthe humidifying apparatus, FIG. 9(b) is a front perspective view, frombelow, of the water tank, FIG. 9(c) is a rear perspective view, frombelow, of the water tank;

FIG. 10(a) is a front perspective view, from above, of a detachablesection of the water tank, FIG. 10(b) is a bottom view of the detachablesection of the water tank, FIG. 10(c) is a top view of the detachablesection of the water tank, FIG. 10(d) is a front perspective view, frombelow, of the detachable section of the water tank, and FIG. 10(e) is arear perspective view, from below, of the detachable section of thewater tank;

FIG. 11(a) is a front view of the base with the detachable section ofthe water tank located on the base, FIG. 11(b) is a front perspectiveview, from above, of the base with the detachable section of the watertank located on the base, FIG. 11(c) is a top view of the base with thedetachable section of the water tank located on the base, and FIG. 11(d)is a section view taken along line L-L in FIG. 11(c);

FIG. 12 is a perspective view, from above, of an impeller of thehumidifying apparatus;

FIG. 13 is a perspective view, from below, of part of the motor housingof the humidifying apparatus;

FIG. 14(a) is a top view of the impeller and motor housing of thehumidifying apparatus, FIG. 14(b) is a sectional view taken along lineJ-J in FIG. 14(a), and FIG. 14(c) is a close up view of area Hidentified in FIG. 14(b);

FIG. 15(a) is a front perspective view, from below, of the base, FIG.15(b) is a similar view to FIG. 15(a), but with a bottom wall of thebase removed, and FIG. 15(c) is a similar view to FIG. 15(b) but with apanel for shielding the drive circuit from water ingress removed;

FIG. 16(a) is a top view of the panel, FIG. 16(b) is a bottom view ofthe panel, FIG. 16(c) is a rear perspective view, from below, of thepanel, and FIG. 16(d) is a rear perspective view, from above, of thepanel; and

FIG. 17 is a schematic illustration of a control system of thehumidifying apparatus.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1 to 3 are external views of a fan assembly. In this example, thefan assembly is in the form of a humidifying apparatus 10. In overview,the humidifying apparatus 10 comprises a body 12 comprising an air inletthrough which air enters the humidifying apparatus 10, and a nozzle 14in the form of an annular casing mounted on the body 12, and whichcomprises a plurality of air outlets for emitting air from thehumidifying apparatus 10.

The nozzle 14 is arranged to emit two different air flows. The nozzle 14comprises a rear section 16 and a front section 18 connected to the rearsection 16. Each section 16, 18 is annular in shape, and extends about abore 20 of the nozzle 14. The bore 20 extends centrally through thenozzle 14 so that the centre of each section 16, 18 is located on theaxis X of the bore 20.

In this example, each section 16, 18 has a “racetrack” shape, in thateach section 16, 18 comprises two, generally straight sections locatedon opposite sides of the bore 20, a curved upper section joining theupper ends of the straight sections and a curved lower section joiningthe lower ends of the straight sections. However, the sections 16, 18may have any desired shape; for example the sections 16, 18 may becircular or oval. In this embodiment, the height of the nozzle 14 isgreater than the width of the nozzle, but the nozzle 14 may beconfigured so that the width of the nozzle 14 is greater than the heightof the nozzle 14.

Each section 16, 18 of the nozzle 14 defines a flow path along which arespective one of the air flows passes. In this embodiment, the rearsection 16 of the nozzle 14 defines a first air flow path along which afirst air flow passes through the nozzle 14, and the front section 18 ofthe nozzle 14 defines a second air flow path along which a second airflow passes through the nozzle 14.

With reference also to FIGS. 4(a) to 5(c), the rear section 16 of thenozzle 14 comprises an annular outer casing section 22 connected to andextending about an annular inner casing section 24. Each casing section22, 24 extends about the bore axis X. Each casing section may be formedfrom a plurality of connected parts, but in this embodiment each casingsection 22, 24 is formed from a respective, single moulded part. Eachcasing section 22, 24 is preferably formed from plastics material. Asshown in FIG. 5(c), the front part of the inner casing section 24 has anannular outer wall 24 a which extends generally parallel to the boreaxis X, a front end wall 24 b and an annular intermediary wall 24 cwhich extends generally perpendicular to the bore axis X and which joinsthe outer wall 24 a to the end wall 24 b so that the end wall 24 b ispositioned forwardly of the intermediary wall 24 c. During assembly, theexternal surface of the outer wall 24 a is connected to the internalsurface of the front end of the outer casing section 22, for exampleusing an adhesive.

The outer casing section 22 comprises a tubular base 26 which defines afirst air inlet 28 of the nozzle 14. The outer casing section 22 and theinner casing section 24 together define a first air outlet 30 of thenozzle 14. As described in more detail below, the first air flow entersthe nozzle 14 through the first air inlet 28, and is emitted from thefirst air outlet 30. The first air outlet 30 is defined by overlapping,or facing, portions of the internal surface 32 of the outer casingsection 22 and the external surface 34 of the inner casing section 24.The first air outlet 30 is in the form of a slot. The slot has arelatively constant width in the range from 0.5 to 5 mm. In this examplethe first air outlet has a width of around 1 mm Spacers 36 may be spacedabout the first air outlet 30 for urging apart the overlapping portionsof the outer casing section 22 and the inner casing section 24 tocontrol the width of the first air outlet 30. These spacers may beintegral with either of the casing sections 22, 24.

In this embodiment, the first air outlet 30 extends partially about thebore 20. The first air outlet 30 extends along the curved upper sectionand the straight sections of the nozzle 14. However, the first airoutlet 30 may extend fully about the bore 20. As shown in FIG. 4(a), thenozzle 14 includes a sealing member 38 for inhibiting the emission ofthe first air flow from the curved lower section of the nozzle 14. Inthis embodiment, the sealing member 38 is generally U-shaped, and isretained by a recess formed in the rear end of the inner casing section24 so as to lie in a plane which is substantially perpendicular to theaxis X. The sealing member 38 engages a U-shaped protrusion 39 extendingforwardly from the rear end of the curved lower section of the outercasing section 22 to form a seal therewith.

The first air outlet 30 is arranged to emit air through a front part ofthe bore 20 of the nozzle 14. The first air outlet 30 is shaped todirect air over an external surface of the nozzle 14. In thisembodiment, the external surface 34 of the inner casing section 24comprises a Coanda surface 40 over which the first air outlet 30 isarranged to direct the first air flow. The Coanda surface 40 is annular,and thus is continuous about the central axis X. The external surface 34of the inner casing section 24 also includes a diffuser portion 42 whichtapers away from the axis X in a direction extending from the first airoutlet 30 to the end wall 24 b of the inner casing section 24.

The casing sections 22, 24 together define an annular first interiorpassage 46 for conveying the first air flow from the first air inlet 28to the first air outlet 30. The first interior passage 46 is defined bythe internal surface of the outer casing section 22 and the internalsurface of the inner casing section 24. A tapering, annular mouth 48 ofthe rear section 16 of the nozzle 14 guides the first air flow to thefirst air outlet 30. A first air flow path through the nozzle 14 maytherefore be considered to be formed from the first air inlet 28, thefirst interior passage 46, the mouth 48 and the first air outlet 30.

The front section 18 of the nozzle 14 comprises an annular front casingsection 50. The front casing section 50 extends about the bore axis X,and has a “racetrack” shape which is similar to that of the other casingsections 22, 24 of the nozzle 14. Similar to the casing sections 22, 24,the front casing section 50 may be formed from a plurality of connectedparts, but in this embodiment the front casing section 50 is formed froma single moulded part. The front casing section 50 is preferably formedfrom plastics material.

The front casing section 50 comprises an annular outer wall 50 a whichextends generally parallel to the bore axis X, and an annular inner wall50 b connected to the outer wall 50 a at the front end 44 of the nozzle14. The inner wall 50 b is angled to the outer wall 50 a so that theinner wall 50 b tapers towards the axis X. During assembly, the frontcasing section 50 is attached to the inner casing section 24, forexample using a series of snap-fit connections between the outer wall 50a of the front casing section 50 and the intermediary wall 24 c of theinner casing section 24. An annular sealing member 52 forms an air-tightseal between the inner casing section 24 and the front casing section50.

With reference to FIG. 6(a), the lower end of the front casing section50 comprises a tubular base 56. The base 56 defines a second air inlet58 of the nozzle 14. The front casing section 50 defines with the innercasing section 24 a second air outlet 60 of the nozzle 14. In thisexample, the second air outlet 60 extends partially about the bore 20,along the curved upper section and the straight sections of the nozzle14. Alternatively, the second air outlet 60 may extend fully about thebore 20. As another alternative, the nozzle 14 may comprise a pluralityof second air outlets, with each of the straight sections of the nozzle14 comprising a respective second air outlet.

In this embodiment, the second air outlet 60 is in the form of a slothaving a relatively constant width in the range from 0.5 to 5 mm. Inthis example the second air outlet 60 has a width of around 1 mm. Thesecond air outlet 60 is located between the end wall 24 b of the innercasing section 24 and the inner wall 50 b of the front casing section50. Spacers 62 may be spaced along the second air outlet 60 to urgeapart the overlapping portions of the inner casing section 24 and thefront casing section 50 to control the width of the second air outlet60. These spacers may be integral with either of the casing sections 24,50. The second air outlet 60 is configured to emit the second air flowinto the bore 20 of the nozzle 14, preferably towards the axis X of thenozzle and more preferably in a plane which is orthogonal to the axis Xof the nozzle 14.

The casing sections 24, 50 together define an annular second interiorpassage 68 for conveying the second air flow from the second air inlet58 to the second air outlet 60. The second interior passage 68 isdefined by the internal surfaces of the inner casing section 24 and thefront casing section 50. A second air flow path through the nozzle 14may therefore be considered to be formed by the second air inlet 58, theinterior passage 68 and the second air outlet 60.

Returning to FIGS. 1 to 3, the body 12 is generally cylindrical inshape. The body 12 comprises a base 70. The base is illustrated in moredetail in FIG. 8. The base 70 has an external outer wall 71 which iscylindrical in shape, and which comprises an air inlet 72. In thisexample, the air inlet 72 comprises a plurality of apertures formed inthe outer wall 71 of the base 70. A front portion of the base 70 maycomprise a user interface of the humidifying apparatus 10. The userinterface is illustrated schematically in FIG. 17, and is described inmore detail below, and comprises at least one user actuable switch orbutton 73 and a drive circuit 74. The drive circuit is indicatedgenerally at 74 in FIGS. 4(a) and 4(d). In FIG. 18, the drive circuit 74is illustrated as a single component, but the drive circuit 74 may beformed from a number of physically separate, but electrically connected,sub-circuits, each comprising a respective processor for controllingvarious different components or functions of the humidifying apparatus10. A detachable mains power cable (not shown) for supplying electricalpower to the humidifying apparatus 10 is connected to the drive circuit74 via a connector 75 a located behind an aperture 75 b formed in theouter wall 71 of the base 70. To connect the drive circuit 74 to themains power supply, the user inserts the cable through the aperture 75 bto connect the cable to the connector 75 a.

With reference also to FIGS. 4(a), 4(d) and 4(e) and FIG. 8, the base 70comprises a first air passageway 76 for conveying a first air flow tothe first air flow path through the nozzle 14, and a second airpassageway 78 for conveying a second air flow to the second air flowpath through the nozzle 14. The first air passageway 76 passes throughthe base 70 from the air inlet 72 to the first air inlet 28 of thenozzle 14. The base 70 comprises a bottom wall 80 connected to the lowerend of the outer wall 71. A sheet 81 of silencing foam is located on theupper surface of the bottom wall 80. A tubular central wall 82, having asmaller diameter than the outer wall 71, is connected to the outer wall71 by an arcuate supporting wall 84. The central wall 82 issubstantially co-axial with the outer wall 71. The supporting wall 84 islocated above, and generally parallel to, the bottom wall 80. Thesupporting wall 84 extends partially about the central wall 82 to definean opening for exposing a water reservoir 140 of the base 70, asdescribed in more detail below. The central wall 82 extends upwardlyaway from the supporting wall 84. In this example, the outer wall 71,central wall 82 and supporting wall 84 are formed as a single componentof the base 70, but alternatively two or more of these walls may beformed as a respective component of the base 70. An upper wall of thebase 70 is connected to the upper end of the central wall 82. The upperwall has a lower frustoconical section 86 and an upper cylindricalsection. The upper cylindrical section comprises a double-skinned wallwhich comprises an outer cylindrical wall 88 a connected to thefrustoconical section 86 and an inner cylindrical wall 88 b into whichthe base 26 of the nozzle 14 is inserted. The walls 88 a, 88 b define anannular housing 88 c within the upper cylindrical section of the base70.

The central wall 82 extends about an impeller 90 for generating a firstair flow through the first air passageway 76. In this example theimpeller 90 is in the form of a mixed flow impeller. In overview, theimpeller 90 is connected to a rotary shaft extending outwardly from amotor 92 for driving the impeller 90. In this embodiment, the motor 92is a DC brushless motor having a speed which is variable by the drivecircuit 74 in response to a speed selection by a user. The maximum speedof the motor 92 is preferably in the range from 5,000 to 10,000 rpm. Themotor 92 is housed within a motor bucket comprising a domed upperportion 96 connected to a lower portion 98. A set of guide vanes 100 isconnected to the upper surface of the upper portion 96 of the motorbucket to guide air towards the first air inlet 28 of the nozzle 14.Further features of the impeller 92 and the motor bucket are describedbelow.

The motor bucket is located within, and mounted on, a generallyfrustoconical impeller housing 104. The impeller housing 104 is, inturn, mounted on an annular platform 106 extending inwardly from thecentral wall 82. An annular inlet member 108 is connected to the bottomof the impeller housing 104 for guiding the air flow into the impellerhousing 104. An annular sealing member 110 is located between theimpeller housing 104 and the platform 106 to prevent air from passingaround the outer surface of the impeller housing 104 to the inlet member108. The platform 106 preferably comprises a guide portion for guidingan electrical cable 107 from the drive circuit 74 to the motor 92.

The first air passageway 76 extends from the air inlet 72 to the inletmember 108. From the inlet member 108, the first air passageway 76extends, in turn, through the impeller housing 104, the upper end of thecentral wall 82 and the sections 86, 88 of the upper wall. Afrustoconical baffle 109 a connected to the internal surfaces of thesections 86, 88 of the upper walls serves to guide the first air flowemitted from the impeller housing 104 into the base 26 of the nozzle 14.An annular seal 109 b extending around the upper end of the baffle 109 aengages the end of the base 26 of the nozzle 14 to form an air tightseal between the nozzle 14 and the base 70.

The second air passageway 78 is arranged to receive air from the firstair passageway 76. The second air passageway 78 is located adjacent tothe first air passageway 76. The second air passageway 78 comprises aduct 110 for receiving air from the first air passageway 76. The duct110 has an annular inlet port 112 located downstream from the guidevanes 100 so as to receive part of the air flow emitted from the guidevanes 100, and which forms the second air flow. The inlet port 112 islocated between the baffle 109 a and a domed upper section 113 of theimpeller housing 104. The duct 110 extends between the impeller housing104 and the baffle 109 a to an outlet port 114 located on the centralwall 82 of the base 70.

The humidifying apparatus 10 is configured to increase the humidity ofthe second air flow before it enters the nozzle 14. With reference nowto FIGS. 1 to 4 and FIGS. 9 to 11, the humidifying apparatus 10comprises a water tank 120 removably mountable on the base 70 of thebody 12. The water tank 120 has a cylindrical outer wall 122 which hasthe same radius as the outer wall 71 of the base 70 of the body 12 sothat the body 12 has a cylindrical appearance when the water tank 120 ismounted on the base 70. The water tank 120 has a tubular inner wall 124which surrounds the walls 82, 86, 88 of the base 70 when the water tank120 is mounted on the base 70. The outer wall 122 and the inner wall 124define, with an annular upper wall 126 and an annular lower wall 128 ofthe water tank 120, an annular volume for storing water. The water tank120 thus surrounds the impeller 90 and the motor 92, and so at leastpart of the first air passageway 76, when the water tank 120 is mountedon the base 70.

The outer wall 122 is formed from material which is transparent tovisible light to allow a user to observe the volume of water storedwithin the water tank 120. For the same reason, the upper wall 126 ispreferably formed from the same material as the outer wall 122. Theouter wall 122 and the upper wall 126 may be joined together using anadhesive, or using a laser welding technique. These walls 122, 126 arepreferably formed from a transparent plastics material. The inner wall124 and the lower wall 128 are preferably integral, and do not need tobe formed from the same plastics material as the outer wall 122 and theupper wall 126. In this embodiment the inner wall 124 and the lower wall128 are formed from material which is opaque to ultraviolet radiation,and preferably also visible light, so that the portion of the base 70which is surrounded by, or covered by, the inner wall 124 and the lowerwall 128 is not visible to the user when the water tank 120 is mountedon the base 70. An adhesive is used to connect the inner wall 124 to theupper wall 126, and to connect the outer wall 122 to the lower wall 128.

The lower wall 128 of the water tank 120 engages, and is supported by,the supporting wall 84 of the base 70 when the water tank 120 is mountedon the base 70. Protrusions 130 may be formed on, or mounted on, thelower wall 128 for location within recesses 132 formed on the supportingwall 84 of the base 70 to ensure accurate angular positioning of thewater tank 120 on the base 70. The protrusions 130 may be in the form ofmagnets which interact with other magnets (not shown) mounted beneaththe recesses 132 on the lower surface of the supporting wall 84 toassist with the accurate location of the water tank 120 on the base 70,and to increase the force required to move the water tank 120 relativeto the base 70. This can reduce the risk of accidental movement of thewater tank 120 relative to the base 70.

The water tank 120 preferably has a capacity in the range from 2 to 4liters. With particular reference to FIGS. 9(b) and 9(c), a spout 134 isremovably connected to the lower wall 128 of the water tank 120, forexample through co-operating threaded connections. In this example thewater tank 120 is filled by removing the water tank 120 from the base 70and inverting the water tank 120 so that the spout 134 is projectingupwardly. The spout 134 is then unscrewed from the water tank 120 andwater is introduced into the water tank 120 through an aperture exposedwhen the spout 134 is disconnected from the water tank 120. The spout134 preferably comprises a plurality of radial fins for facilitating thegripping and twisting of the spout 134 relative to the water tank 120.Once the water tank 120 has been filled, the user reconnects the spout134 to the water tank 120, returns the water tank 120 to itsnon-inverted orientation and replaces the water tank 120 on the base 70.A spring-loaded valve 136 is located within the spout 134 for preventingleakage of water through a water outlet of the spout 134 when the watertank 120 is re-inverted. The valve 136 is biased towards a position inwhich a skirt of the valve 136 engages the upper surface of the spout134 to prevent water entering the spout 134 from the water tank 120.

The upper wall 126 of the water tank 120 comprises one or more supports138 for supporting the inverted water tank 120 on a work surface,counter top or other support surface. In this example, two parallelsupports 138 are formed in the periphery of the upper wall 126 forsupporting the inverted water tank 120.

With reference now to FIGS. 4 and 8, the base 70 comprises a waterreservoir 140 for receiving water from the water tank 120. The waterreservoir 140 is a separate component which is connected to the lowersurface of the supporting wall 84 of the base 70, and which is exposedby the opening formed in the supporting wall 84. The water reservoir 140comprises an inlet chamber 142 for receiving water from the water tank120, and an outlet chamber 144 for receiving water from the inletchamber 142, and in which water is atomised to become entrained withinthe second air flow. The inlet chamber 142 is located on one side of thewater reservoir 140, and the outlet chamber 144 is located on the otherside of the water reservoir 140. The water reservoir 140 comprises abase and a side wall extending about and upstanding from the peripheryof the base. The base is shaped so that the depth of the outlet chamber144 is greater than the depth of the inlet chamber 142. The sections ofthe base located within each chamber 142, 144 are preferablysubstantially parallel, and are preferably parallel to the bottom wall80 of the base 70 so that these sections of the base are substantiallyhorizontal when the humidifying apparatus 10 is located on a horizontalsupport surface. A channel 150 formed in the water reservoir 140 allowswater to pass from the inlet chamber 142 to the outlet chamber 144.

A pin 152 extends upwardly from the section of the base forming, inpart, the inlet chamber 142. When the water tank 120 is mounted on thebase 70, the pin 152 protrudes into the spout 134 to push the valve 136upwardly to open the spout 134, thereby allowing water to pass undergravity into the inlet chamber 142. As the inlet chamber 142 fills withwater, water passes through the channel 150 to enter the outlet chamber144. As water is output from the water tank 120, it is replaced withinthe water tank 120 by air which enters the water tank 120 through slots154 located in the side wall of the spout 134. As the chambers 142, 144fill with water, the level of water within the chambers 142, 144equalizes. The spout 134 is arranged so that the water reservoir 140 canbe filled with water to a maximum level which is substantially co-planarwith the upper end of the slots 154 located within the side wall of thespout 134; above that level no air can enter the water tank 120 toreplace water output from the water tank 120.

The section of the base forming, in part, the outlet chamber 144comprises a circular aperture for exposing a piezoelectric transducer156. The drive circuit 74 is configured to actuate vibration of thetransducer 156 in an atomization mode to atomise water located in theoutlet chamber 144. In the atomization mode, the transducer 156 mayvibrate ultrasonically at a frequency f₁, which may be in the range from1 to 2 MHz. With reference also to FIG. 15(b), the transducer 156 formspart of a piezoelectric transducer assembly 157 which is connected tothe lower side of the bottom wall 80 of the base 70 so as to protrudethrough an aperture formed in the bottom wall 80 of the base 70. Wires158 connect the transducer 156 to the drive circuit 74.

The water reservoir 140 also includes an ultraviolet radiation (UV)generator for irradiating water within the water reservoir 140. In thisembodiment, the UV generator is arranged to irradiate water within theoutlet chamber 144 of the water reservoir 140. In this embodiment, theUV generator comprises a UV lamp 160, which forms part of a UV lampassembly 162 of the base 70. The UV lamp assembly 162 is in the form ofa cartridge which is removably insertable into the base 70 to allow theUV lamp assembly 162 to be replaced by a user as required. The waterreservoir 140 comprises a UV transparent tube 164. The tube 164 islocated within the outlet chamber 144 of the water reservoir 140. The UVlamp assembly 162 is supported by the base 70 so that the UV lamp 160 islocated within the tube 164 when it is inserted fully into the base 70.Preferably, an open end of the tube 164 protrudes through an apertureformed in the side wall of the water reservoir 140 to allow the UV lamp160 to enter the tube 164. An 0-ring sealing member may be providedbetween the tube 164 and the aperture formed in the side wall to inhibitwater leakage through the aperture.

With reference to FIGS. 15(a) and 15(b), the bottom wall 80 of the base70 comprises an aperture through which the transducer assembly 157 andthe UV lamp assembly 162 are inserted into, and removable from, the base70. The aperture is normally covered by a panel 166 removably connectedto the lower side of the bottom wall 80 of the base 70. By removing thepanel 166 from the bottom wall 80 of the base 70, a user is able toaccess both the UV lamp assembly 162 and the piezoelectric transducerassembly 157 for replacement or repair of each assembly as required.

A float 168 may be provided within the water tank 120, and a levelsensor 170, shown schematically in FIG. 17, may be provided in the base70 for detecting the position of the float 168 and so provide a signalwhich is indicative of the level of the water in the water tank 120. Thebase 70 may also include a proximity sensor 172 for detecting that thewater tank 120 has been mounted on the base 70. The proximity sensor 172may be in the form of a Hall effect sensor which interacts with a magnet(not shown) located on the lower wall 128 of the water tank 120 todetect the presence, or absence, of the water tank 120 on the base 70.

The water tank 120 defines an inlet duct 174 for receiving the secondair flow from the outlet port 114 of the base 70. In this embodiment,the inlet duct 174 is defined by a detachable section 176 of the watertank 120, which is detachably connected to the inner wall 124 of thewater tank 120 by a user-operable catch 177. The detachable section 176is illustrated in FIG. 10; FIG. 11 illustrates the position of thedetachable section 176 relative to the base 70 when the water tank 120is mounted on the base 70. The detachable section 176 comprises a body178 which is formed from material which is opaque to ultravioletradiation, and is preferably moulded from plastics material. The inletduct 174 passes through the body 178 from an air inlet 180 to an airoutlet 182. The air inlet 180 of the inlet duct 174 is positioned in aside wall of the body 178 so that it is positioned opposite to theoutlet port 114 located on the central wall 82 of the base 70 when thewater tank 120 is mounted on the base 70, as shown in FIG. 4(b). The airoutlet 182 of the inlet duct 174 is located in a bottom wall 184 of thebody 178 so that it is located above the water reservoir 140. Themaximum water level of the water reservoir 140 is preferably selected sothat the air outlet 182 lies above this maximum water level. As aresult, the second air flow enters the water reservoir 140 directly overthe surface of the water located in the outlet chamber 144 of the waterreservoir 140.

The water tank 120 also includes an outlet duct for conveying the secondair flow from the reservoir 140 to the second air inlet 58 of the nozzle14. In the embodiment, the outlet duct comprises an inlet section 186and an outlet section 188. The inlet section 186 is defined by thedetachable section 176 of the water tank 120. The detachable section 176comprises an air inlet 190 of the outlet duct. The air inlet 190 islocated in the bottom wall 184 of the body 178 so that it is positioneddirectly above the transducer 156 when the water tank 120 is mounted onthe base 70, as shown in FIGS. 11(c) and 11(d). Consequently, a columnof water generated during the actuation of the transducer 156 can enterthe inlet section 186 of the outlet duct, and so ensure that mist-likewater particles generated in the vicinity of the water column can becomeentrained within the second air flow. The air inlet 190 of the outletduct is preferably substantially co-planar with the air outlet 182 ofthe inlet duct 174, and is preferably located adjacent to the air outlet182 of the inlet duct 174 so as to minimise the length of the flow pathbetween the air outlet 182 of the inlet duct 174 and the air inlet 190of the outlet duct.

The body 178 of the detachable section 176 comprises a flange 192 whichextends outwardly from the bottom wall 184. The flange 192 extendsaround a majority of the body 178. The flange 192 is shaped so that whenthe water tank 120 is mounted on the base 70, the flange 192 is locatedover, and is preferably mounted upon, a recessed portion 194 of thesupporting wall 84 which extends about the water reservoir 140. As shownthrough a comparison of FIGS. 8(a) to 8(d) to FIGS. 11(a) to 11(d), theflange 192 serves to occlude a peripheral portion 196 of the outletchamber 144 of the water reservoir 140, and so inhibits the leakage ofultraviolet radiation from this peripheral portion 196 of the outletchamber 144 during operation of the UV lamp 160.

The detachable section 176 comprises a wall 198 depending from theflange 192 for guiding the second air flow from the air outlet 182 ofthe inlet duct 174 towards the air inlet 190 of the outlet duct. Thewall 198 is annular in shape and positioned so as to delimit, and so toextend about, a flow channel located directly beneath the air outlet 182of the inlet duct 174 and the air inlet 190 of the outlet duct. Theheight of the wall 198 is selected so that when the outlet chamber 144of the water reservoir 140 is filled with water to the maximum level,the end of the wall 198 extends into the water stored in the outletchamber 144, establishing an interface between the wall 198 and thestored water which forms a seal for inhibiting the leakage of the secondair flow from the flow channel defined by the wall 198.

The body 178 of the detachable section 176 comprises a port 200 fromwhich the second air flow enters the outlet section 188 from the inletsection 186. When the detachable section 176 is connected to the innerwall 124 of the water tank 120, an inner part of the outlet section 188is defined by the detachable section 176, and an outer part of theoutlet section 188 is defined by the inner wall 124. A seal 202 disposedon the detachable section 176 forms an air tight seal to prevent leakageof the second air flow from the interface between the inner wall 124 andthe detachable section 176. In this embodiment, the outlet section 188of the outlet duct bifurcates to form a pair of duct branches 204, eachcomprising a respective air outlet 206 of the outlet duct. This allowsthe outlet duct to convey the second air flow about part of the base 70,in this embodiment a button 260 (described in more detail below)actuable by the user to release the nozzle 14 from the base 70.

With reference to FIGS. 4(a) and 9(a), the water tank 120 comprises aseal 210 for engaging the base 56 of the nozzle 14. In FIG. 9(a), theseal 210 is illustrated as being detached from the remainder of thewater tank 120 to allow features of the seal 210 to be seen. The seal210 is supported by a support 212 which is integral with the inner wall124 of the water tank 120. The seal 210 is detachably connected to thesupport 212 to allow a user to remove the seal for cleaning andreplacement. For example, the seal 210 may comprises a pair of resilientfingers 214 which, when the seal 210 is connected to the support 212,extend through an aperture 216 formed in the support 212. When the seal210 is to be removed from the support 212, the fingers 214 may bepinched together by the user to allow the fingers 214 to pass throughthe aperture 216 as the seal 210 is pulled away from the support 212.The fingers 214 are connected to a relatively rigid frame 218 of theseal 210. The frame 218 is shaped so as to surround the end of the base56 of the nozzle 14.

The frame 218 carries a relatively flexible, resilient part of the seal210. The resilient part of the seal 210 comprises a first section 220which is retained by, and surrounded by, the frame 218 for engaging theend of the base 56 of the nozzle 14. The resilient part of the seal 210also comprises a pair of second sections 222 depending from the firstsection 220, and which engage the support 212 to urge the frame 218 awayfrom the support 212 and towards the base 56 of the nozzle 14. The seal210 and the support 212 comprise apertures or passageways 224 whichallow the second air flow to pass therethrough and into the base 56 ofthe nozzle 14. In this embodiment, each of the second sections 222 istubular in shape, and has an undulating or bellows shape.

As illustrated in FIG. 4, when the water tank 120 is mounted on the base70 the inner wall 124 surrounds the upper wall of the base 70 to exposethe open upper end of the upper cylindrical section of the upper wall.The water tank 120 includes a handle 230 to facilitate removal of thewater tank 120 from the base 70. The handle 230 is pivotably connectedto the water tank 120 so as to be moveable relative to the water tank120 between a stowed position, in which the handle 230 is housed withina recessed section 232 of the water tank 120, and a deployed position,in which the handle 230 is raised above the upper wall 126 of the watertank 120 so that it may be gripped by a user.

When the nozzle 14 is mounted on the body 12, the base 26 of the outercasing section 22 of the nozzle 14 is located over the open end of theupper cylindrical section of the upper wall of the base 70, and the base56 of the front casing section 50 of the nozzle 14 is located over theseal 210 of the water tank 120. The user then pushes the nozzle 14towards the body 12. When the bases 26, 56 of the nozzle 14 are fullyinserted in the body 12, the annular seal 109 b engages the end of thebase 26 of the nozzle 14 to form an air tight seal between the nozzle 14and the base 70, whereas the seal 210 engages the end of the base 56 ofthe nozzle 14 to form an air tight seal between the nozzle 14 and thewater tank 120.

With reference now to FIG. 4(c) and FIGS. 6 to 8, the body 12 comprisesa sensor 240 for detecting the position of the nozzle 14 relative to thebody 12. The sensor 240 is connected to the drive circuit 74, which isconfigured to inhibit the actuation of the UV lamp 160 unless the signalreceived from the sensor 240 indicates that the nozzle 14 has beeninserted fully on to the body 12. In this example, the nozzle 14comprises a magnet 242, and the sensor 240 is in the form of a Halleffect sensor which generates a signal which is indicative of thedetected strength of the magnetic field generated by the magnet 242. Thesensor 240 is located in the housing 88 c defined by the cylindricalwalls 88 a, 88 b of the base 70 of the body 12, and the magnet 242 islocated on the base 26 of the nozzle 14 so that the magnet 242 islocated adjacent to the sensor 240 when the base 26 of the nozzle 14 hasbeen inserted fully into the base 70 of the body 12.

The base 26 of the nozzle 14 includes a housing 244 for retaining themagnet 242. The housing 244 is located on the outer surface of the base26. The housing 244 has an annular wall which is integral with the base26, and which defines at least side walls 246, a lower end wall 248 andan upper end wall of the housing 248. The housing 244 may have one of avariety of other shapers, such as rectangular or other polygonal shape,and so the annular wall may be replaced with a series of connected wallswhich define the side walls 246 and ends wall of the housing 244. Thewalls of the housing 244 surround the magnet 242. A cover 250 isconnected to the walls of the housing 244 by snap fit connectors.

The inner cylindrical wall 88 b of the base 70 comprises a groove 252which is shaped to receive the housing 244 as the nozzle 14 is mountedon the body 12. The sensor 242 is positioned within the housing 88 c soas to be located between the groove 252 and outer cylindrical wall 88 a.The groove 252 and the housing 244 have substantially the same shape sothat the nozzle 14 becomes angularly aligned relative to the body 12 asthe base 26 of the nozzle 14 is inserted into the body 12. The groove252 comprises side walls 254 for engaging the side walls 246 of thehousing 244 to inhibit relative rotation between the nozzle 14 and thebody 12, and an end wall 256 for engaging the lower end wall 248 of thehousing 244 to restrict the extent to which the housing 244 isinsertable within the groove 252.

With reference to FIG. 4(f) and FIGS. 6 to 8, a mechanism is providedfor releasably retaining the nozzle 14 on the body 12. In overview, thebody 12 comprises a button 260, detents 262 for engaging the nozzle 14,and an annular actuator 264. The detents 262 are mounted within thehousing 88 c of the base 70 so as to be moveable relative to the base 70between a retaining position for retaining the nozzle 14 on the body 12,and a release position for releasing the nozzle 14 for removal from thebody 12. Each detent 262 is pivotably mounted within the housing 88 c,and is biased by a spring 265 towards the retaining position in whicheach detent 262 protrudes through an aperture formed in the wall 88 b ofthe base 70. The detents 262 are diametrically opposed. As the usermounts the nozzle 14 on the body 12, the detents 262 are urged away fromtheir retaining positions by the base 26 of the nozzle 14 to allow thebase 26 of the nozzle 14 to enter the base 70 of the body 12. The base26 of the nozzle 14 comprises a pair of diametrically-opposed recesses266 which become angularly aligned with the detents 262 as the nozzle 14is inserted into the body 12. When the nozzle 14 is inserted fully intothe body 12, the detents 262 enter the grooves 266, under the biasingforce of their springs 265, to retain the nozzle 14 on the body 12unless the user depresses the button 260.

The actuator 264 is in the form of a non-circular hoop located withinthe cavity 88 c for engaging the detents 262. The button 260 and theactuator 264 are arranged so that the depression of the button 260 bythe user causes the actuator 264 to rotate within the cavity 88 c. Forexample, the actuator 264 may comprise a protrusion 264 a which iscontacted, and pushed to one side, by the button 260 as it is depressedby the user, which causes the actuator 264 to rotate in a clockwisedirection within the housing 88 c. Due to the asymmetric shape of theactuator 264, the rotation of the actuator 264 causes it to engage thedetents 262 to move the detents 262 away from the grooves 266, againstthe biasing force of the springs 265, to their release positions. Thisallows the user to remove the nozzle 14 from the body 12. Once thenozzle 14 has been lifted from the body 12, the button 260 may bereleased by the user. The springs 265 urge the detents 262 back to theirretaining position, which in turn causes the actuator 264 to rotatewithin the housing 88 c in an anticlockwise direction and raise thebutton 260.

When the nozzle 14 has been removed from the body 12, the user mayremove the water tank 120 from the base 70, for example to replenish thewater tank 120 or to remove the detachable section 176 and seal 210 forcleaning. While the nozzle 14 is removed from the body 12, there is anopportunity for water to enter the body 12 through the exposed first airpassageway 76, especially when the water tank 120 is replaced on thebase 70. For example, with reference to FIGS. 4(e), 13 and 14, waterdroplets may fall on the exposed upper surface of the upper portion 96of the motor bucket. To prevent these water droplets from running downthe motor bucket and entering components of the motor or motor bearings,the lower portion 98 of the motor bucket comprises an annular lip 270which forms an annular drip edge which extends around the motor bucket.As a result, any water droplets which run down the side of the motorbucket will fall away from the motor 92 and into the impeller 90.

The impeller 90 comprise a substantially conical hub 272 and a series ofcurved vanes 274 which are connected to, and preferably integral with,the outer surface of the hub 272. In this embodiment, the impeller 90further comprises a generally frustoconical shroud 276 which isconnected to the outer edges of the curved vanes 274. If any waterdroplets fall from the lip 270, those water droplets will fall into theimpeller 90, between the hub 272 and the shroud 276. The droplets willsubsequently fall from the impeller 90, through the inlet member 108 andon to the sheet 81 of silencing foam. To minimise any disruption to theair flow generated by the rotation of the impeller 90, the lip 270 doesnot protrude downwardly from the motor bucket beyond the hub 272 of theimpeller 90.

The lip 270 is defined by an outer peripheral wall of an annular groove278 formed in the lower portion of the motor bucket. The impeller 90comprises an annular vane 280 connected to the base of the hub 272 so asto extend into the groove 278. In this embodiment, each of the groove278 and the vane 280 is annular in shape. During rotation of theimpeller 90, the vane 280 generates an air boundary adjacent to the lip270 which further inhibits the passage of water droplets along the lowerportion 98 of the motor bucket beyond the lip 270.

Returning to FIG. 4(d), and with reference also to FIGS. 15 and 16, thedrive circuit 74 is located within the base 70. The drive circuit 74 isconnected by means of screws to the lower surface of the annularsupporting wall 84 of the base 70. As illustrated in FIG. 15(c), thedrive circuit 74 is thus sited in close proximity to the air inlet 72 ofthe apparatus 10. To prevent the drive circuit 74 from becoming exposedto any moisture or other matter which enters the base 70 through the airinlet 72, the base 70 comprises a panel 290 which is connected to thesupporting wall 84 so as to shield the drive circuit 74 from the airflow passing from the air inlet 72 to the inlet member 108.

The panel 290 is illustrated in isolation in FIG. 16, whereas FIG. 15(b)illustrates the panel 290 in situ within the base 70. The panel 290 hasgenerally the same shape as the drive circuit 74, and comprises aC-shaped body 292 and a raised wall 294 extending upwardly from theperiphery of the body 292. The body 292 has a number of raised sectionsof different shape to accommodate various different components of thedrive circuit 74.

The panel 290 comprises a trough 296 which is located beneath theconnector 75 a to which the mains power cable is attached by the user.As there is a risk that water may enter the base 70 through the aperture75 b when the mains power cable is disconnected from the base 70, thetrough 296 comprises a drain hole 298 for draining any such water fromthe trough 296.

As described above, a button 73 for controlling the operation of thehumidifying apparatus may be located on the outer wall 71 of the base 70of the body 12. The button 73 may be used to activate and deactivate themotor 92 to switch on and switch off the humidifying apparatus.Additionally, the humidifying apparatus 10 comprises a remote control300 for transmitting control signals to a user interface circuit 302 ofthe humidifying apparatus 10. FIG. 17 illustrates schematically acontrol system for the humidifying apparatus 10, which includes theremote control 300, the user interface circuit 302 and other electricalcomponents of the humidifying apparatus 10. In overview, the remotecontrol 300 comprises a plurality of buttons which are depressible bythe user, and a control unit for generating and transmitting infraredlight signals in response to depression of one of the buttons. Theinfrared light signals are emitted from a window located at one end ofthe remote control 300. The control unit is powered by a battery locatedwithin a battery housing of the remote control 300.

A first button is used to activate and deactivate the motor 92, and asecond button is used to set the speed of the motor 92, and thus therotational speed of the impeller 90. The control system may have adiscrete number of user selectable speed settings, each corresponding toa respective different rotational speed of the motor 92. A third buttonis used to set a desired level for the relative humidity of theenvironment in which the humidifying apparatus 10 is located, such as aroom, office or other domestic environment. For example, the desiredrelative humidity level may be selected within a range from 30 to 80% at20° C. through repeated actuation of the third button. A fourth buttonmay be used to selectively deactivate the transducer 156 to prevent thesecond air flow from becoming humidified.

The user interface circuit 302 comprises a switch which is actuatedthrough user operation of the button 73, a sensor or receiver 304 forreceiving signals transmitted by the remote control 300, and a display306 for displaying a current operational setting of the humidifyingapparatus 10. For example, the display 306 may normally indicate thecurrently selected relative humidity level. As the user changes therotational speed of the motor 92, the display 306 may indicate brieflythe currently selected speed setting. The display 306 may be locatedimmediately behind a transparent or translucent part of the outer wall71 of the base 70, and the sensor 304 may be located behind the button73.

The user interface circuit 302 is connected to the drive circuit 74. Thedrive circuit 74 comprises a microprocessor and a motor driver fordriving the motor 92. A mains power cable (not shown) for supplyingelectrical power to the humidifying apparatus 10 extends through theaperture 75 b formed in the base 70. The cable is connected to a plug.The drive circuit 74 comprises a power supply unit connected to theconnector 75 a. The user interface may also comprise one or more LEDsfor providing a visual alert depending on a status of the humidifyingapparatus 10. For example, a first LED 308 may be illuminated toindicate that the water tank 120 has become depleted, as indicated by asignal received by the drive circuit 74 from the level sensor 170.

A humidity sensor 310 is also provided for detecting the relativehumidity of air in the external environment, and for supplying a signalindicative of the detected relative humidity to the drive circuit 74. Inthis example the humidity sensor 310 may be located immediately behindthe air inlet 72 to detect the relative humidity of the air flow drawninto the humidifying apparatus 10. The user interface may comprise asecond LED 312 which is illuminated by the drive circuit 74 when anoutput from the humidity sensor 310 indicates that the relative humidityof the air flow entering the humidifying apparatus 10, HD, is at orabove the desired relative humidity level, HS, set by the user.

To operate the humidifying apparatus 10, the user actuates the firstbutton of the remote control, in response to which the remote control300 generates a signal containing data indicative of the actuation ofthis first button. This signal is received by the receiver 304 of theuser interface circuit 302. The operation of the button is communicatedby the user interface circuit 302 to the drive circuit 74, in responseto which the drive circuit 74 actuates the UV lamp 160 to irradiatewater stored in the outlet chamber 144 of the water reservoir 140. Inthis example, the drive circuit 74 simultaneously activates the motor 92to rotate the impeller 90. The rotation of the impeller 90 causes air tobe drawn into the body 12 through the air inlet 72. An air flow passesthrough the impeller housing 104 and the guide vanes 100. Downstreamfrom the guide vanes 100, a portion of the air emitted from the guidevanes 100 enters the duct 110, whereas the remainder of the air emittedfrom the guide vanes 100 is conveyed along the first air passageway 76to the first air inlet 28 of the nozzle 14. The impeller 90 and themotor 92 may thus be considered to generate a first air flow which isconveyed to the nozzle 14 by the first air passageway 76 and whichenters the nozzle 14 through the first air inlet 28.

The first air flow enters the first interior passage 46 at the lower endthereof. The first air flow is divided into two air streams which passin opposite directions around the bore 20 of the nozzle 14. As the airstreams pass through the first interior passage 46, air enters the mouth48 of the nozzle 14. The air flow rate into the mouth 48 is preferablysubstantially even about the bore 20 of the nozzle 14. The mouth 48guides the air flow towards the first air outlet 30 of the nozzle 14,from where it is emitted from the humidifying apparatus 10.

The air flow emitted from the first air outlet 30 causes a secondary airflow to be generated by the entrainment of air from the externalenvironment, specifically from the region around the first air outlet 30and from around the rear of the nozzle 14. Some of this secondary airflow passes through the bore 20 of the nozzle 14, whereas the remainderof the secondary air flow becomes entrained, in front of the nozzle 14,within the air flow emitted from the first air outlet 30.

As mentioned above, with rotation of the impeller 90 air enters thesecond air passageway 78 to form a second air flow. The second air flowpasses through the duct 110 and the inlet duct 174 of the detachablesection 176 of the water tank 120 to be emitted over the water stored inthe outlet chamber 144 of the water reservoir 140. When the drivecircuit 74 actuates the vibration of the transducer 156 to atomize waterstored in the outlet chamber 144 of the water reservoir 140, airbornewater droplets above the water located within the outlet chamber 144 ofthe water reservoir 140. The transducer 156 may be actuated in responseto a user input received from the remote control 300, and/or a fixedtime period following the actuation of the motor 92 to create the airflows through the humidifying apparatus 10.

With rotation of the impeller 90, airborne water droplets becomeentrained within the second air flow. The—now moist—second air flowpasses upwardly through the outlet duct to the second air inlet 58 ofthe nozzle 14, and enters the second interior passage 68 within thefront section 18 of the nozzle 14.

At the base of the second interior passage 68, the second air flow isdivided into two air streams which pass in opposite directions aroundthe bore 20 of the nozzle 14. As the air streams pass through the secondinterior passage 68, each air stream is emitted from the second airoutlet 60. The emitted second air flow is conveyed away from thehumidifying apparatus 10 within the air flow generated through theemission of the first air flow from the nozzle 14, thereby enabling ahumid air current to be experienced rapidly at a distance of severalmetres from the humidifying apparatus 10.

The moist air flow is emitted from the nozzle 14 until the relativehumidity HD of the air flow entering the humidifying apparatus 10, asdetected by the humidity sensor 310, is 1% at 20° C. higher than therelative humidity level HS, selected by the user using the third buttonof the remote control 270. The emission of the moistened air flow fromthe nozzle 14 may then be terminated by the drive circuit 74, preferablyby changing the mode of vibration of the transducer 156. For example,the frequency of the vibration of the transducer 156 may be reduced to afrequency f3, where f1>f3≧0, below which atomization of the stored wateris not performed. Alternatively the amplitude of the vibrations of thetransducer 156 may be reduced. Optionally, the motor 92 may also bestopped so that no air flow is emitted from the nozzle 14. However, whenthe humidity sensor 310 is located in close proximity to the motor 92 itis preferred that the motor 92 is operated continually to avoidundesirable humidity fluctuation in the local environment of thehumidity sensor 310.

As a result of the termination of the emission of a moist air flow fromthe humidifying apparatus 10, the relative humidity HD detected by thehumidity sensor 310 will begin to fall. Once the relative humidity ofthe air of the environment local to the humidity sensor 270 has fallento 1% at 20° C. below the relative humidity level HS selected by theuser, the drive circuit 74 re-activates the vibration of the transducer156 in the atomization mode. If the motor 92 has been stopped, the drivecircuit 74 simultaneously re-activates the motor 92. As before, themoist air flow is emitted from the nozzle 14 until the relative humidityHD detected by the humidity sensor 310 is 1% at 20° C. higher than therelative humidity level HS selected by the user.

This actuation sequence of the transducer 156 (and optionally the motor92) for maintaining the detected humidity level around the levelselected by the user continues until the first button is actuated again,or until a signal is received from the level sensor 170 indicating thatthe level of water within the water tank 120 has fallen below theminimum level. If the first button is actuated, or upon receipt of thissignal from the level sensor 170, the drive circuit 74 deactivates themotor 92, the transducer 156 and the UV lamp 160 to switch off thehumidifying apparatus 10. The drive circuit 74 also deactivates thesecomponents of the humidifying apparatus 10 in response to a signalreceived from the proximity sensor 172 indicating that the water tank120 has been removed from the base 70, and in response to a signalreceived from the sensor 240 indicating that the nozzle 14 has beenremoved from the base 70.

The invention claimed is:
 1. A humidifying apparatus comprising: a basecomprising a chamber; a water tank removably mounted on the base forsupplying water to the chamber; an impeller and a motor for driving theimpeller to generate an air flow; an inlet duct for conveying the airflow to the chamber; a humidifier for humidifying the air flow withwater from the chamber; an ultraviolet radiation generator forirradiating water stored in the chamber; and an outlet duct forconveying the humidified air flow from the chamber; wherein a detachablesection of the apparatus is opaque to ultraviolet radiation and ispositioned over the chamber when the water tank is mounted on the base,the detachable section comprising an air inlet of the outlet duct and aflange for occluding a peripheral portion of the chamber.
 2. Thehumidifying apparatus of claim 1, wherein the detachable section of theapparatus is detachably connected to the water tank.
 3. The humidifyingapparatus of claim 1, wherein the detachable section comprises an airoutlet of the inlet duct.
 4. The humidifying apparatus of claim 3,wherein the air outlet of the inlet duct is co-planar with the air inletof the outlet duct.
 5. The humidifying apparatus of claim 3, wherein theair outlet of the inlet duct is located adjacent to the air inlet of theoutlet duct.
 6. The humidifying apparatus of claim 5, wherein thedetachable section comprises a wall depending from at least part of theflange for guiding the air flow from the air outlet of the inlet ducttowards the air inlet of the outlet duct.
 7. The humidifying apparatusof claim 6, wherein the wall is annular in shape and positioned so as toextend about a flow channel located directly beneath the air outlet ofthe inlet duct and the air inlet of the outlet duct.
 8. The humidifyingapparatus of claim 6, wherein when the chamber is filled with water to amaximum level, the wall extends into the water stored in the chamber. 9.The humidifying apparatus of claim 3, wherein the detachable sectioncomprises an air inlet of the inlet duct, and wherein the base comprisesan air passageway for conveying the air flow from the impeller to theair inlet of the inlet duct.
 10. The humidifying apparatus of claim 1,wherein the humidifier comprises a transducer for atomizing water storedin the chamber, and wherein the air inlet of the outlet duct is locateddirectly above the transducer.
 11. The humidifying apparatus of claim 1,wherein the water tank is annular in shape, and comprises an annularinner wall which is opaque to ultraviolet radiation and an annular outerwall which is transparent to visible light, and wherein the detachablesection of the apparatus is detachably connected to the annular innerwall of the water tank.
 12. The humidifying apparatus of claim 1,wherein the outlet duct comprises an inlet section and an outletsection, and wherein the detachable section of the apparatus defines theinlet section of the outlet duct, and the detachable section of theapparatus and the annular inner wall of the water tank together definethe outlet section of the outlet duct.
 13. The humidifying apparatus ofclaim 1, comprising an air outlet detachably mounted on the base, and areleasing device for releasing the air outlet for removal from the base,the releasing device comprising a user operable button mounted on thebase, and wherein the outlet duct is bifurcated into a pair of ductbranches, the button being positioned between the duct branches.
 14. Thehumidifying apparatus of claim 13, wherein the water tank comprises aseal for engaging the air outlet and a support for supporting the seal,and wherein the detachable section of the apparatus is detachablyconnected to the support.
 15. The humidifying apparatus of claim 14,wherein the seal is biased towards the air outlet.
 16. The humidifyingapparatus of claim 15, wherein the seal comprises a relatively rigidframe and a relatively flexible, resilient part for engaging the airoutlet and for urging the frame towards the air outlet.
 17. Thehumidifying apparatus of claim 16, wherein the frame is connected to theseal so as to allow movement of the frame relative to the support, theresilient part of the seal being arranged to engage the support so as tourge the frame away from the support.
 18. The humidifying apparatus ofclaim 16, wherein each of the support and the seal comprises at leastone aperture for conveying the humidified air flow from the outlet ductto the air outlet.